THREE UNPUBLISHED PAPERS BY BLYTH. 325 



Cypselus leuconyx of India, quite distinct from the nearlj'- allied 

 C. vittatus of the countries lying eastward of the Bay of Bengal ; 

 and a similar distinction probably exists between Mr. Strickland's 

 large and blacker Malacca variety of C. offinis and the bird so 

 called of India, the more especially as C. affinis is a permanently 

 resident species, which does not appear to be subject to any 

 variation, and moreover does not seem to inhabit the intervening 

 Burmese countries. Lastly, we have a remarkable fact in the 

 respective limitation of range of the two large species of Acan- 

 thylis, neither of which has hitherto been observed in the regions 

 inhabited or visited by the other, though both are known to be 

 migratory. The times of arrival and departure of the various 

 migrant species in different parts of the country, north and south 

 especially, and in mountains or valleys, require to be noticed and 

 recorded. 



PS. — Since the foregoing paper was printed we have seen Sir 

 Everard Home's article on the subject of the gastric glands of 

 what he supposed to be the edible nest-building " Swallow," pub- 

 lished in the 'Philosophical Transactions,' vol. cvii. (1817), 

 p. 332. He mentions that Sir S. Eaffles had given him some of 

 the nests, concerning the composition of which that observer 

 " gave it decidedly as his own opinion that, whatever it is, it is 

 brought up from the stomach, and requires at times so great an 

 effort as to bring up blood, the stain of which is seen on the 

 nest." But it does not appear that Sir S. Baffles supplied the 

 specimen of the bird examined by Home, which could scarcely 

 be of the genus Collocalia, if, as Sir E. Home states, " This bird 

 is double the size of our common Swallow," i. e., Hirundo rustica, 

 a statement which is confirmed by his fig. 1 of the plate, " magni- 

 fied twice in diameter, or four times in superficies," and repre- 

 senting accordingly the stomach of a much larger bird than any 

 known species of Collocalia. The structure of the proventricular 

 glands figured by Home, as those of the producer of the edible 

 nests, is so very curious and remarkable, and withal so con- 

 spicuously different from the structure ordinarily observable in 

 the class, that we imagined we could not well have overlooked it 

 even with the naked eye ; and, upon submitting the gastric glands 

 of Collocalia fucix)ha(ja, Cypselus affinis, and C. balasiensis to 

 microscopical inspection, we found in neither of these species a 



